Pipe bursting is a known technique for replacing underground pipe, such as sewer, water and gas lines, without having to dig a trench to remove the old pipe and position a new one. In pipe bursting, a bursting head or mole is pushed or pulled through the old pipe to burst or slit the old pipe while, usually concurrently, feeding a replacement pipe into position. The replacement pipe is typically flexible and is preferably high density polyethylene (HDPE).
Initially, most pipe bursting apparatus employed winches, pulleys, and other relatively large components in order to develop the necessary forces. Such equipment also typically required relatively large excavations at either end of the section of pipe being replaced in order to position the equipment properly.
Later, however, advancements in design, an example of which is shown and described in U.S. Pat. No. 6,305,880, resulted in smaller, lighter weight equipment. Smaller excavations were required at either end of the pipe segment being replaced, and the equipment could be manually positioned for use. This opened the way for pipe bursting to be used for smaller applications, such as the replacement of residential lateral sewer and water lines.
Still, apparatus for pipe bursting in smaller applications remains relatively large, heavy, and complex. As a consequence, there are physical difficulties in the handling of such equipment, and significant costs in materials and manufacturing. Also, because of the high forces required in the pulling process, high pressure hydraulics were typically employed, further adding to the manufacturing cost.
Accordingly, there is a need for a pipe bursting apparatus which is low in cost and complexity, easier to handle and set up, and capable of operating with lower pressure hydraulics.